JP2001193703A - Hydraulic control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and the cost of a hydraulic control device used in a lift cylinder or the like. SOLUTION: A valve body V comprises a selector valve 3 formed of a spool 2 slidably built in, and a compensator valve 4 formed of a valve element 23 built in the valve body V, separately from the selector valve 3. Since the compensator valve 4 functions also as a down control valve, the need for specially installing a down control valve is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device of a load sensing control circuit used for, for example, a lift cylinder.

[0002]

2. Description of the Related Art For example, when lowering a lift cylinder, it is operated slowly. The operation is performed slowly at the time of descending in order to secure sufficient safety. Conventionally,
In order to control the operation of the lift cylinder in this way,
A special down control valve was provided. The down control valve supplies pressure oil to the bottom chamber of the cylinder via the check valve when ascending, and reduces the flow rate passing through the orifice when descending to reduce the pressure oil in the bottom chamber of the cylinder. It is intended to be dropped.

[0003]

As described above, conventionally, a down control valve is specially provided to control the flow rate when the lift cylinder is lowered. Therefore, there is a problem that the entire hydraulic control device is increased in size by the amount of the down control valve. Further, there is a problem that the cost increases as the number of valves to be assembled increases. SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic control device capable of safely reducing a lift cylinder, for example, in which the entire device can be reduced in size and cost can be reduced.

[0004]

According to the hydraulic control device of the present invention, a spool is slidably incorporated in a valve body to constitute a switching valve, and the switching valve is provided with an inflow port according to a switching position of the spool. And the actuator port, or the inflow port and the tank port, and the throttle opening between the inflow port and the actuator port or the inflow port and the tank port according to the amount of spool switching. On the other hand, a compensator valve is configured by incorporating a valve body different from the spool into the valve body, and the compensator valve is a switching valve having one of the pressure chambers located upstream of the throttle. Hydraulic control device, which communicates with the inflow port of the An inflow passage communicating with the one pressure chamber of the compensator valve is formed in the valve body, and the inflow passage is communicated with the actuator port or the pump port in accordance with the moving position of the spool. It has a special feature.

[0005]

FIG. 1 shows an embodiment of the present invention. The valve body V of this embodiment has an actuator port 1 connected to an actuator (not shown).
, A pump port PP communicating with the pump, and a tank port TP communicating with the tank are formed. In this embodiment, the actuator is a lift cylinder,
The actuator port 1 is connected to the bottom chamber of the lift cylinder.

Further, a switching valve 3 formed by a spool 2 slidably incorporated in the valve body V,
In addition to the switching valve 3, a compensator valve 4 formed by a valve body 23 incorporated in the valve body V is provided. The compensator valve 4 controls a differential pressure before and after a flow rate passing through a metering notch formed in the switching valve 3. Outside the spool 2, the valve body V communicates with the supply passage 5 communicating with the pump port PP, the inflow passage 6 communicating with the upstream side of the compensator valve 4, and the downstream side of the compensator valve 4. An inflow port 7, an annular recess 8, and a tank port TP are formed.

A communication passage formed of communication passages 9a and 9b is formed in the inside of the spool 2 in the axial direction. Then, annular grooves 10, 11, 12, and 13 are formed on the outer periphery of the spool 2. A diaphragm R1 is formed by the annular groove 11 and a metering notch 14a opening in the annular groove 11, and a metering notch 14b opening in the annular groove 12 and the annular groove 12.
The aperture R2 is formed by the above. Further, a through hole 15 communicating with the annular groove 11 is provided in the communication passage 9a, and a through hole 16 is provided in the communication passage 9b.
Is formed. The annular groove 10 always communicates with the supply path 5, and the annular groove 11 always communicates with the actuator port 1.

Further, the compensator valve 4 controls the flow rate supplied from the inflow passage 6 by the differential pressure between the upstream side and the downstream side of the throttle R1 or R2 as follows. That is, the pressure on the upstream side of the throttle R1 or R2 is guided to the pressure receiving chamber 17. Then, the pressure on the downstream side of the throttle R <b> 1 or R <b> 2 is guided to the pressure receiving chamber 18. The pressure guided to the pressure receiving chamber 18 is guided through a passage 21 communicating with the annular recess 8 and an orifice 22 communicating with the passage 21. Then, the pressure receiving chamber 1 that has led the pressure downstream of the throttle
8 is provided with a spring 19.

Therefore, the compensator valve 4 is
The valve body 23 of the compensator valve 4 is moved up and down so that the flow rate flowing from the inflow passage 6 to the inflow port 7 is controlled so that the pressure on the upstream side of the throttle always increases by the spring force of the spring 19. FIG. 1 shows a state in which the compensator valve 4 is pressed by the spring 19 and is in contact with the stopper 20, that is, a state in which the compensator valve 4 is fully opened.

In such a hydraulic control apparatus, when the spool 2 is switched to the right in order to raise the lift cylinder, the pressure oil supplied from the pump passes through the supply path 5 from the pump port PP to the annular groove 10. Through the inflow passage 6. Then, the pressure oil is guided to the pressure receiving chamber 17, and is supplied from the inflow port 7 to the metering notch 14.
a, It is supplied to the actuator port 1 through the annular groove 11.

On the other hand, the oil that has entered the annular groove 11
Through the communication passage 9a, through the communication passage 9b, and from the communication passage 9b to the passage 21 through the through hole 16. And this oil pressure, that is, the metering notch 14
a from the pressure receiving chamber 18 via the orifice 22.
It is led to. At this time, the compensator valve 4 supplies a flow rate corresponding to the opening of the annular groove 11 and the metering notch 14a, that is, the opening of the throttle R1. When the spool 2 is switched to the right as described above, the pressure oil is supplied to the bottom chamber side of the lift cylinder (not shown) connected to the actuator port 1, the lift cylinder rises, and the flow rate supplied to the lift cylinder is also controlled. .

When the spool 2 is switched to the left to lower the lift cylinder, the pump port PP
Since the communication between the supply passage 5 and the inflow passage 6 communicating with the communication port is interrupted, the pressure oil is not supplied to the actuator port 1. At this time, the actuator port 1 and the supply channel 6 communicate with each other via the annular groove 11, and the inflow port 7 and the annular recess 8 which communicate with the supply channel 6 communicate with each other via the metering notch 14b and the annular groove 12. Communicate. The annular recess 8 communicates with the tank port TP via the annular groove 13. Therefore, the pressure oil in the bottom chamber of the lift cylinder flows along the communication path as described above, and drops to the pump.

Further, the pressure on the downstream side of the throttle R2 formed by the metering notch 14b and the annular groove 12 is applied to the pressure receiving chamber 1 from the annular recess 8 via the passage 21 and the orifice 22.
It is led to 8. On the other hand, what is guided to the pressure receiving chamber 17 is the pressure oil upstream of the throttle R2. At this time, the compensator valve 4 controls the flow rate flowing from the inflow passage 6 to the inflow port 7 so as to keep the differential pressure before and after the throttle R2 constant. That is, the compensator valve 4 controls the flow rate of the oil that falls from the bottom chamber side of the lift cylinder to the tank to be constant.

According to this embodiment, the return flow from the lift cylinder can be controlled by the compensator valve 4 for controlling the amount of oil supplied to the actuator, so that a special down control valve is not required. Being able to control the return flow means that the lowering speed of the cylinder can also be controlled. Therefore, the size of the entire hydraulic control device can be reduced because the down control valve need not be provided. Further, the cost can be reduced by reducing the number of valves to be assembled.

[0015]

According to the present invention, the control of the flow rate supplied to the lift cylinder by the compensator valve and the control of the flow rate of the flow returning from the lift cylinder to the tank are also used. There is no need to provide it separately. Therefore, the size of the entire control device can be reduced because the down control valve is not provided. Moreover, the number of assembly points of the control device is reduced, so that the cost can be reduced.

[0016]

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic control device showing an embodiment of the present invention.

[Explanation of symbols]

 V Valve body PP Pump port TP Tank port R1 Restrictor R2 Restrictor 1 Actuator port 2 Spool 3 Switching valve 4 Compensator valve 5 Supply path 9a Communication path 9b Communication path 14a Metering notch 14b Metering notch 17 Pressure receiving chamber 18 Pressure receiving chamber 19 Spring 23 Valve body

Claims (1)

[Claims] A switching valve is constructed by slidably incorporating a spool into a valve body, and the switching valve communicates an inflow port with an actuator port or an inflow port according to a switching position of the spool. And the tank port are communicated with each other, and the throttle opening between the inflow port and the actuator port or the inflow port and the tank port is controlled in accordance with the spool switching amount. A compensator valve is configured by incorporating a separate valve body from the spool, and this compensator valve communicates one pressure chamber with the inflow port of a switching valve located upstream of the throttle and connects the other pressure chamber with the other pressure chamber. In the hydraulic pressure control device communicating with the flow path downstream of the throttle, the one pressure chamber of the compensator valve A hydraulic control device, wherein a communicating inflow passage is formed in a valve body, and the inflow passage is communicated with an actuator port or a pump port in accordance with a movement position of a spool.